Mao Haotian, Weichman Kathleen, Gong Zheng, Ditmire Todd, Quevedo Hernan, Arefiev Alexey
Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, California 92093, USA.
Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, California 92093, USA and University of Rochester, Laboratory for Laser Energetics, Rochester, New York 14623, USA.
Phys Rev E. 2021 Feb;103(2-1):023209. doi: 10.1103/PhysRevE.103.023209.
A high energy density plasma embedded in a neutral gas is able to launch an outward-propagating nonlinear electrostatic ionization wave that traps energetic electrons. The trapping maintains a strong sheath electric field, enabling rapid and long-lasting wave propagation aided by field ionization. Using 1D3V kinetic simulations, we examine the propagation of the ionization wave in the presence of a transverse MG-level magnetic field with the objective to identify qualitative changes in a regime where the initial thermal pressure of the plasma exceeds the pressure of the magnetic field (β>1). Our key finding is that the magnetic field stops the propagation by causing the energetic electrons sustaining the wave to lose their energy by emitting an electromagnetic wave. The emission is accompanied by the magnetic field expulsion from the plasma and an increased electron loss from the trapping wave structure. The described effect provides a mechanism mitigating rapid plasma expansion for those applications that involve an embedded plasma, such as high-flux neutron production from laser-irradiated deuterium gas jets.
嵌入中性气体中的高能量密度等离子体能够引发向外传播的非线性静电电离波，该波会捕获高能电子。这种捕获维持着强鞘层电场，使得在场致电离的辅助下，波能够快速且持久地传播。利用一维三维动力学模拟，我们研究了在存在横向MG量级磁场的情况下电离波的传播，目的是识别在等离子体初始热压力超过磁场压力（β>1）的区域内的定性变化。我们的关键发现是，磁场通过使维持波的高能电子发射电磁波而失去能量，从而阻止波的传播。这种发射伴随着磁场从等离子体中排出以及捕获波结构中电子损失的增加。所描述的效应为那些涉及嵌入式等离子体的应用提供了一种减轻等离子体快速膨胀的机制，例如从激光辐照的氘气喷流中产生高通量中子。
